I'm using django-extensions and I ran shell_plus --kernel and it output:
To connect another client to this kernel, use:
--existing kernel-6690.json
Then I tried connecting with Jupyter:
$ jupyter notebook --existing=kernel-6690.json
[W 10:44:59.290 NotebookApp] Unrecognized alias: '--existing=kernel-6690.json', it will probably have no effect.
...
Why doesn't Jupyter connect to the kernel?
Reviewing https://github.com/ipython/ipython/issues/4066, it appears that the notebook is not able to connect to kernels. In other words for all the talk about how Jupyter notebook is separated into a kernel and frontend it's actually not and this information is not written in any documentation I could find.
Jupyter notebook does not support connecting to an existing kernel. shell_plus --notebook does close enough to what I want.